As promised , this thread will be dedicated to the conversion of the three stage intake manifold from the e90 330i to the e90/92 328i and 325i. This has been proven to be the most power yielding modification for those who do not own 330s.

From what I could gather, this conversion paired with a tune would increase power to approximately ~265hp and ~225 lbft tq at the flywheel (stock 330i is 255hp/220tq) due to the benefits of the tune, minus the losses from a more restrictive exhaust system on the 25i/28i. Remember, 330i's have freer flowing catalytic converters.

This modification allows 325s to achieve at least ~40hp, and 328s to achieve at least ~35hpgains, rendering this upgrade the most cost effective for non-330 N52s.

I have seen more power yielded from this upgrade; it's dependent on the tune/tuning company you use.

Here are the parts with part numbers of what is needed (credits to e90pilot):

**As far as warranty goes, the setup looks stock, sans the extra wires connected to the DISA valves, but the tune may be detectable. For this reason, I don't endorse completing this mod under warranty. Almost all 325's are out of warranty at this point, though, with 328's following suit.**

I hope to run into one of these modded 325/328is sometime, although I doubt it will happen in the KC area. Look forward to seeing you guys get the power increases you deserve!

Thats the spirit

Nothing would put a smile more than the 325 keeping up with, if not beating the 330. If this does work, which am almost positive it will, it would render my higher mileage 330xi obsolete, which then i will be able to sell and use the funds to buy a very tempting 335i.

That said, I plan on continuing with my mission to create the quickest 325 and to help others with theirs.

1. the 128 is still under warranty
2. the 128i has enough power in my opinion
3. the 325 is severely underpowered, also in my opinion
4. the 330xi is most likely going to be replaced with a 335 soon and im keeping one naturally aspirated 3 series project car next to the turbo 3er

I will probably do this to the 128 later down the line, but the DIY and writeup going to be using the 325